<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      // string 转数值
      var a = '100'
      console.log(a + 0) // 1000 字符串型
      console.log(a - 0) // 100 整数型
    </script>
  </body>
</html>
